Booking a bucket-list Trans-Siberian rail journey in September will earn you three extra days exploring the art, architecture and history of beautiful St Petersburg at no extra cost.

Trans-Siberian train specialist Flower Travel is offering the free St Petersburg extension package to those booking the 2018 Tsars Gold itinerary from Beijing to Moscow (or the return) in a Bolshoi Platinum cabin or Bolshoi cabin by September 30.

The 15-day trip on the Tsars Gold Private Train is a once in a lifetime journey reliving the classic era of rail travel with attentive service, sumptuous menus and luxurious décor.

Travelling between May and September along this historic route, you will experience spectacular scenery including the Gobi Desert, Siberia’s mountainous steppes, Lake Baikal and historical cities from the comfort of a private train.

Join your train guide and a local English-speaking guide in small touring parties for overnight city stays to explore The Great Wall of China, the Forbidden City, Yekaterinburg where Russian Tsar Nicholas II and his family were murdered, and Moscow by night to see Red Square with its colourful St Basil’s Cathedral.

Along the way, you will see Mongolian horse riding at a yurt camp, a Buddhist ceremony at the Gandan Monastery, explore the World Heritage-listed Kazan Kremlin, discover Tatar mosques and marvel at Russian Orthodox cathedrals.

Life on board the Tsars Gold Private Train is relaxing with plenty of time to read, play cards, chat to fellow passengers, attend lectures, indulge in a Russian feast with vodka tasting and enjoy leisurely breakfasts as you admire the spectacular scenery.

The luxurious Bolshoi Platinum and Bolshoi Cabins have private facilities, and guests stay in five-star hotels in Moscow and Beijing where they travel in guided groups of no more than 12.

The Tsars Gold Private Train also has a 16-day itinerary from Moscow to Beijing. Prices for 2018 start from AU$17,332.

The St Petersburg extension package includes a high-speed train transfer from Moscow, two nights at a luxury hotel with breakfast and hotel transfers. This package usually costs $895 per person.